Question: $ { \left[\begin{array}{rr}{4} & {2} \\ {-2} & {1}\end{array}\right]-\left[\begin{array}{rr}{3} & {1} \\ {-2} & {-1}\end{array}\right] = {?} } $
Answer: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{4}-{3} & {2}-{1} \\ {-2}-{-2} & {1}-{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{1} & {1} \\ {0} & {2}\end{array}\right]}$